1. Field of the Invention
The present invention relates to an air gap device for a water softener system, and particularly to an air gap device adapted for attachment to both relatively small and relatively large standard size waste standpipes, whether they are made of plastic or metal, or are threaded or unthreaded.
2. Description of the Prior Art
A typical household water softener continuously treats incoming water by passing it through a resin composition. Water flow through the composition is periodically interrupted so that the resin composition can be flushed with salt water to rejuvenate it. Backsiphoning of the waste water flow into the household potable water system is prevented by passing the waste flow through an air gap device prior to discharging it into the waste standpipe.
The discharge of waste from a typical household reverse osmosis system must also be directed through an air gap device to prevent backsiphoning. Although it is not mandatory, it is desirable that both the water softener and reverse osmosis waste water discharges be directed through one air gap device for simplicity of operation, reduced cost and ease of installation. Various devices are available in the prior art to accomplish this, one such device being disclosed in my U.S. Pat. No. 5,592,964. Analogous arrangements are disclosed in my U.S. Pat. No. 5,176,165, and in U.S. Pat. No. 3,411,524 issued to Robert E. Raine and to the present applicant.
The waste standpipe is usually located somewhere close to the water softener drain line but it can be located elsewhere, and in some cases extends into a wall box which is recessed into the wall for convenience.
Most standpipes are made of galvanized steel pipe or polyvinyl chloride plastic, and are typically made available in a smaller diameter standard size of one and one-half inches, and a larger diameter standard size of two inches. Of course, other materials and sizes can be used if desired, but the two mentioned are very commonly used.
Insofar as applicant is aware, there are no air gap devices in the prior art that are adapted for connection to both threaded and unthreaded metal and plastic waste standpipes of different standard sizes.
Thus, if the air gap device has a threaded end fitting for threaded connection to a threaded standpipe, it will fit only one size of standpipe. Additional air gap devices are required for each different size, presenting a stocking problem for both sellers and users.
On the other hand, if the air gap device is not threaded but has a slip fit end, it can only be connected to a threaded standpipe if it is forced onto or within the threads of the standpipe, depending upon the diameter of the standpipe. However, this would not be desirable, particularly in the absence of a generous overlap of the parts, because the air gap device could be accidentally separated from the standpipe, and also because water could leak past the threaded area of the standpipe.
If the standpipe and air gap device are both unthreaded and made of plastic, they can be permanently slip fitted together by using a suitable adhesive.